Major bottlenecks for therapeutic application of polypeptides are their limited solubility, in vivo stability, short serum half-life and fast clearance from the bloodstream.
Different approaches are reported to address these drawbacks. However, none of these technologies provides for a robust and universal platform that enables pharmacokinetic (PK) modulation without encountering immunogenicity risks or potential loss of biological activity.
One approach to improve PK/stability and biophysical behavior of therapeutic polypeptides is to fuse them to entities which stabilized the polypeptide, keep it in solution, and extend its half-life. Examples of such entities are human serum albumin or human immunoglobulin Fc-regions. This approach is applicable to many linear polypeptides that are composed of naturally occurring amino acid residues and that tolerate modifications at either their C- or N-terminus without losing their biological activity. Polypeptides that are cyclic, stapled, contain non-natural amino acid residues, or additional modifications cannot be recombinantly produced as fusion polypeptides. However, such polypeptides may be the desired choice for therapeutic applications because they are frequently superior to ‘normal’ linear peptides in terms of protease stability, activity and specificity.
One approach to improve PK/stability and biophysical behavior of therapeutic polypeptides, which can also be applied to those that are cyclic, stapled, or contain non-natural structures, is the chemical or enzymatic conjugation to polymers, for example by PEGylation or HESylation. However, such modifications frequently lead to significant reduction of the biological activity of the polypeptide and can under certain circumstances be the reason for safety or toxicity problems.
A major disadvantage of most existing chemical coupling technologies for stabilization or PK modulation of therapeutic polypeptides is their complexity. Beside the chemical coupling step the methods result in many cases in a mixture of polypeptide derivatives that are connected to the PK-modulating entity with uncertain stoichiometries and/or at undefined positions. Additionally currently used polypeptide modification-technologies often result in strongly reduced or even complete loss of biological activity of the therapeutic polypeptide. In addition, it is difficult to predict pharmacological properties and/or possible degradation routes of the chemical conjugates.
The helicar element is composed of a 12-mer amino acids peptide forming an α-helix. The structural elements of the peptide are described in Nygaard et al. reporting also an anti-helicar antibody and the complex structure with the 12-mer peptide, part of a yeast leucine zipper protein called GCN4. The antibody portion Fv has been affinity matured using the phage display technique to an affinity of 25 pM (Zahnd, C., et al., J. Biol. Chem. 279 (2004) 18870-18877). Metz, S., et al. (Proc. Natl. Acad. Sci. USA 108 (2011) 8194-8424) report bispecific digoxigenin-binding antibodies for targeted payload delivery. PK modulation of haptenylated peptides via non-covalent antibody complexation is reported by Hoffmann, E., et al. (J. Contr. Rel. 171 (2013) 48-56). In WO 2012/093068 a pharmaceutical composition of a complex of an anti-dig antibody and digoxigenin that is conjugated to a peptide is reported. Directed in vitro evolution and crystallographic analysis of a peptide-binding single chain antibody fragment (scFv) with low picomolar affinity is reported by Zahnd, C., et al. (J. Biol. Chem. 279 (2004) 18870-18877). Hanes, J., et al. (Proc. Natl. Acad. Sci. USA 95 (1998) 14130-14135) report that ribosome display efficiently selects and evolves high-affinity antibodies in vitro from immune libraries.
U.S. Pat. No. 5,804,371 reports hapten-labeled peptides and their use in an immunological method of detection. A digoxigenin-labeled peptide (Bradykinin) and its application to chemiluminoenzyme immunoassay of Bradykinin in inflamed tissues are reported by Decarie A., et al. (Peptides 15 (1994) 511-518).
In WO 2004/065569 multi-functional antibodies are reported.
In WO 2014/006124 covalent hapten-anti-hapten antibody complexes are reported.